1. Field of the Invention
The present invention pertains to devices for applying a liquid composition to the surface of an image member in an electrographic processor.
2. Description of the Prior Art
Multiple-slit liquid applicator heads for electrographic image processors, such as the heads described in U.S. Pat. Nos. 3,407,786 and 3,929,099 are well-known. Such heads comprise a base member connected to a supply of a liquid composition, and a cover member. The base member has interlaced supply and drain grooves separated by raised lands. The cover member has perforations through which the liquid composition flows from the supply grooves to the drain grooves.
Hitherto, the manufacture of these heads has required expensive machining techniques to provide the precise control of the liquid flow pattern produced by the head. This precise control is necessary to prevent streaking and mottling of the images developed by the processor. The perforations in the surface of these heads must be accurately formed. The surface must also be precisely flat. If these conditions are met the pressure of the liquid between the applicator head and an image member moving across the head can maintain the image member at a uniform distance from the head. A distance within the range of 0.5 to 2 mm is generally optimum. If this distance is uniform, the effect of the applicator head on the image memer's electrostatic charge and the quantity of the developer provided by the applicator head to the image member will be uniform.
The surface of the applicator heads should be made of a corrosion and abrasion-resistant material and preferably are electrically conductive. Stainless steel sheet has been used, but stainless steel sheet thick enough to provide a rigid planar surface must be cut or punched and then machined to assure that the cut or punched sheet provides a smooth, planar surface.